I recently had a new air conditioner installed and the proposal was for a Trane 2-ton R410 unit. They installed a Trane 2-ton R22 unit. I caught this a couple weeks after the unit was fully installed. I have no problems with the R22 unit, as it runs fine. The installer is willing to work with me to remedy the situation, but I am unsure what a fair offer would be. Should I have them re-install a new unit? He has offered to extend the labor warranty from 1 year to 5 years? Should I ask for a partial refund? What would be a fair amount? Looking for some good advice.

The R22 unit probably works better and may have been cheaper. R22 will get more expensive as time goes on, so it's a pay now or pay later type of thing.

The labor warrany really doesn't cost him anything. Because it's his mistake, I think he should eat the difference AND give you the extended labor warranty for the screw up.

Your contract probably states an R410A unit and you probably could take him to court to honor that. Replacing with an R410A unit will cost him lots of bucks.

If they did not change the indoor coil they will have to if they go from R-22 to R-410. The 410 coil is larger.